In addition to its inflammatory potential (three fold more edematogenic than SpV – Fig. 5B), previous

investigations revealed that F2 fraction was active on isolated rat hearts and presents hemolytic activity (Andrich et al., 2010; Gomes et al., 2010). This wide array of pharmacological properties exhibited by F2, and also the presence of a major protein band of ca 90 kDa (see Gomes ABT-199 research buy et al., 2010), support the proposal that the active component of this fraction is Sp-CTx, a vasoactive and cytolytic toxin previously purified from this venom (Andrich et al., 2010). Interestingly, inflammatory activity was also observed in a latter eluted fraction (F6, Fig. 5), corresponding to low molecular mass components. Mediators of small molecular mass were described in several fish venoms (Church and Hodgson, 2002; Garnier et al., 1996), including histamine-like compounds (Haavaldsen and Fonum, 1963). Since a partial blockade of SpV edema inducing activity was observed initially using promethazine (Fig. 4, KU-57788 mouse 0.5 h), a histamine H1 receptor antagonist, it is possible that F6 fraction contains histamine-like compounds, which would contribute to the onset of the inflammatory reaction using SpV. Taken together, our results suggest that the acute local inflammatory effects evoked

by S. plumieri venom are associated with an indirect activation of the KKS. However, the action of kallikrein-like enzymes could not be discarded and may be relevant in a chronic response model, such as that observed in human envenomation. Other low molecular mass mediators seem to contribute with the onset of the inflammatory response. In addition, these data corroborate with the hypothesis that, similar to stonefish venoms, the edema induced by scorpionfish venom could be associated with a multifunctional, heat-labile ( Fig. 1) and membrane-perturbing toxin, probably Sp-CTx. Nevertheless, this proposition should be confirmed

further. In conclusion, the present work investigated in mice the inflammatory response caused by the venom of scorpionfish S. plumieri, which is able to release pro-inflammatory MG-132 price cytokines (TNF and IL-6), a chemokine (MCP-1) and induces an inflammatory cell infiltrate constituted mainly by neutrophils and mononuclear cells. Our results clearly demonstrate that the KKS plays a fundamental role on the edema evoked by S. plumieri venom. In addition, a proteic fraction, that contains a multifunctional toxin and reproduced the edematogenic effect of the SpV, was partially purified. Further investigations (including a chronic approach) are required to complete elucidate the mechanisms of the inflammatory response involved. A better understanding of the fish venom action could lead us to the development of new therapeutic strategies complementary to conventional therapy that has been used nowadays.